Part of our Getting On The Air: Modes, Operations, and Making Contacts guide.
One of the nicest things about the IC-7300 Mark II for digital modes is what you don’t need: no Digirig, no SignaLink, no separate USB-to-serial cable. The radio has a built-in USB audio codec and CAT interface, and the Mark II upgraded that to USB Type-C with dual virtual COM ports. One cable handles everything. Here’s the full setup.
What you’ll need
- Icom IC-7300 Mark II
- A USB-C cable to your computer
- Icom’s USB driver (Silicon Labs based), free download from Icom’s website
- WSJT-X installed
Connecting to the computer
- Install the Icom USB driver before you plug anything in, this creates the virtual COM ports Windows needs to see the radio as a serial device.
- Connect the USB-C cable from the radio to your computer and power the radio on.
- Open Device Manager. You should see two devices appear: a USB audio device (the radio’s built-in sound card) and, under Ports (COM & LPT), one or two virtual COM ports depending on driver version, the Mark II’s dual virtual COM ports let you dedicate one to CAT control and one to PTT/data if your software supports it, though WSJT-X only needs the one for CAT since it handles PTT over the same CAT connection.
- Note the COM port number; you’ll need it for WSJT-X.
Radio menu settings
A handful of settings matter for clean digital operation:
- Mode: set to USB-D (the “D” data submode), the radio won’t transmit digital audio correctly without it
- Filter (FIL1): around 3kHz is a reasonable data bandwidth
- DATA OFF MOD: MIC/ACC (keeps the front mic from also feeding into transmit while in data mode)
- DATA MOD: USB (routes the data audio input from the USB connection rather than the ACC jack)
- USB Serial Function: CI-V
- CI-V Address: check Menu → SET → Connectors → CI-V and note the address shown (this identifies the radio to CAT software)
- CI-V Transceive: ON
- CI-V USB Echo Back: ON, this one specifically matters for WSJT-X to read frequency and mode changes correctly
- RF Power: drop it to roughly 20-40W for digital modes, FT8 runs a high duty cycle and full 100W continuously will run the radio hot
Setting up WSJT-X
- General tab: enter your callsign and grid square.
- Radio tab: set Rig to “Icom IC-7300” (select the closest matching entry if the Mark II isn’t listed separately in your WSJT-X version), Serial Port to the COM port you noted, Baud Rate to match the radio’s CI-V USB baud rate setting, Data Bits 8, Stop Bits 1 or 2, Handshake None. Set PTT Method to CAT, Mode to Data/Pkt, and Split Operation to Rig (or Fake It if you run into split-tuning issues).
- Audio tab: select the radio’s USB Audio CODEC for both input and output.
- Click Test CAT, the radio should briefly key or respond to confirm the link. Test PTT the same way.
Getting on the air with FT8
- Sync your computer’s clock. FT8’s 15-second transmit/receive cycles are locked to UTC; more than a second or two off and you won’t decode or be decoded.
- Tune to a standard FT8 frequency in USB mode, 14.074 MHz on 20m and 7.074 MHz on 40m are consistently active.
- Keep power modest. 20-40W is plenty; FT8 is a weak-signal mode by design and doesn’t reward running high power.
- Watch your ALC, not just your power setting. Adjust the USB MOD Level so the ALC meter barely moves. Overdriving the audio causes splatter without actually improving your odds of being decoded.
Making your first contact
Once decodes start populating the left-hand panel, double-click any station calling CQ. WSJT-X takes over the exchange automatically: your callsign, signal reports, and acknowledgment all get sent and received across the following 15-second cycles. Watch the right-hand panel to follow the QSO in progress; once “73” is logged, you’ve completed a contact.
If nothing’s decoding, check the clock sync first, it’s the most common culprit. After that, confirm the audio input is actually showing signal in WSJT-X (there’s a level indicator on the main screen) and that you’re on an active frequency for the time of day and band conditions.
Once you’re making contacts, GridTracker and the IC-7300 Mark II covers automatic logging, and our IC-7300 Mark II Complete Guide rounds up everything else for this radio. And since the IC-7300’s native CI-V panadapter is one of the radios best supported by it, see my review of Nexus if you want a single free program to handle your decoding, logging, and rig control together.